Hemelipoglycoprotein from the ornate sheep tick, dermacentor marginatus: structural and functional characterization

<p>Abstract</p> <p>Background</p> <p>Tick carrier proteins are able to bind, transport, and store host-blood heme, and thus they function also as antioxidants. Nevertheless, the role of carrier proteins in ticks is not fully understood. Some of them are found also in tick males which do not feed on hosts to such an extent such as females (there are differences in male feeding in different tick species) and thus they are not dealing with such an excess of heme; some of the carrier proteins were found in salivary glands where the processing of blood and thus release of heme does not occur. Besides, the carrier proteins bind relatively low amounts of heme (in one case only two molecules of heme per protein) compared to their sizes (above 200 kDa).</p> <p>The main aim of this study is the biochemical characterization of a carrier protein from the ornate sheep tick <it>Dermacentor marginatus</it>, hemelipoglycoprotein, with emphasis on its size in native conditions, its glycosylation and identification of its modifying glycans, and examining its carbohydrate-binding specificity.</p> <p>Results</p> <p>Hemelipoglycoprotein from <it>D. marginatus </it>plasma was purified in native state by immunoprecipitation and denatured using electroelution from SDS-PAGE separated plasma. The protein (290 kDa) contains two subunits with molecular weights 100 and 95 kDa. It is glycosylated by high-mannose and complex <it>N</it>-glycans HexNAc₂Hex₉, HexNAc₂Hex₁₀, HexNAc₄Hex₇, and HexNAc₄Hex₈. The purified protein is able to agglutinate red blood cells and has galactose- and mannose-binding specificity. The protein is recognized by antibodies directed against plasma proteins with hemagglutination activity and against fibrinogen-related lectin Dorin M from the tick <it>Ornithodoros moubata</it>.</p> <p>It forms high-molecular weight complexes with putative fibrinogen-related proteins and other unknown proteins under native conditions in tick plasma. Feeding does not increase its amounts in male plasma. The hemelipoglycoprotein was detected also in hemocytes, salivary glands, and gut. In salivary glands, the protein was present in both glycosylated and nonglycosylated forms.</p> <p>Conclusion</p> <p>A 290 kDa hemelipoglycoprotein from the tick <it>Dermacentor marginatus</it>, was characterized. The protein has two subunits with 95 and 100 kDa, and bears high-mannose and complex <it>N</it>-linked glycans. In hemolymph, it is present in complexes with putative fibrinogen-related proteins. This, together with its carbohydrate-binding activity, suggests its possible involvement in tick innate immunity. In fed female salivary glands, it was found also in a form corresponding to the deglycosylated protein.</p

Corrigendum: Analysis of tick-borne encephalitis virus-induced host responses in human cells of neuronal origin and interferon-mediated protection

No abstract available

Analysis of tick-borne encephalitis virus-induced host responses in human cells of neuronal origin and interferon-mediated protection

Tick-borne encephalitis virus (TBEV) is a member of the genus Flavivirus. It can cause serious infections in humans that may result in encephalitis/meningoencephalitis. Although several studies have described the involvement of specific genes in the host response to TBEV infection in the central nervous system (CNS), the overall network remains poorly characterized. Therefore, we investigated the response of DAOY cells (human medulloblastoma cells derived from cerebellar neurons) to TBEV (Neudoerfl strain, Western subtype) infection to characterize differentially expressed genes by transcriptome analysis. Our results revealed a wide panel of interferon-stimulated genes (ISGs) and pro-inflammatory cytokines, including type III but not type I (or II) interferons (IFNs), which are activated upon TBEV infection, as well as a number of non-coding RNAs, including long non-coding RNAs. To obtain a broader view of the pathways responsible for eliciting an antiviral state in DAOY cells we examined the effect of type I and III IFNs and found that only type I IFN pre-treatment inhibited TBEV production. The cellular response to TBEV showed only partial overlap with gene expression changes induced by IFN-β treatment – suggesting a virus-specific signature – and we identified a group of ISGs that were highly up-regulated following IFN-β treatment. Moreover, a high rate of down-regulation was observed for a wide panel of pro-inflammatory cytokines upon IFN-β treatment. These data can serve as the basis for further studies of host–TBEV interactions and the identification of ISGs and/or lncRNAs with potent antiviral effects in cases of TBEV infection in human neuronal cells

Genomic Resources Notes accepted 1 April 2014 - 31 May 2014

Genomic Resources Development Consortium.This article documents the public availability of a global transcriptome comparison between Lyme disease tick vectors, Ixodes scapularis and Ixodes ricinus.Peer Reviewe

Defensins from the tick Ixodes scapularis are effective against phytopathogenic fungi and the human bacterial pathogen Listeria grayi

This is an Open Access article distributed under the terms of the Creative Commons Attribution License.-- et al.[Background]: Ixodes scapularis is the most common tick species in North America and a vector of important pathogens that cause diseases in humans and animals including Lyme disease, anaplasmosis and babesiosis. Tick defensins have been identified as a new source of antimicrobial agents with putative medical applications due to their wide-ranging antimicrobial activities. Two multigene families of defensins were previously reported in I. scapularis. The objective of the present study was to characterise the potential antimicrobial activity of two defensins from I. scapularis with emphasis on human pathogenic bacterial strains and important phytopathogenic fungi. [Methods]: Scapularisin-3 and Scapularisin-6 mature peptides were chemically synthesised. In vitro antimicrobial assays were performed to test the activity of these two defensins against species of different bacterial genera including Gram-positive bacteria Staphylococcus aureus, Staphylococcus epidermidis, and Listeria spp. as well as Gram-negative bacteria Escherichia coli, Pseudomonas aeruginosa along with two plant-pathogenic fungi from the genus Fusarium. In addition, the tissue-specific expression patterns of Scapularisin-3 and Scapularisin-6 in I. scapularis midgut, salivary glands and embryo-derived cell lines were determined using PCR. Finally, tertiary structures of the two defensins were predicted and structural analyses were conducted. [Results]: Scapularisin-6 efficiently killed L. grayi, and both Scapularisin-3 and Scapularisin-6 caused strong inhibition (IC value: ∼1 μM) of the germination of plant-pathogenic fungi Fusarium culmorum and Fusarium graminearum. Scapularisin-6 gene expression was observed in I. scapularis salivary glands and midgut. However, Scapularisin-3 gene expression was only detected in the salivary glands. Transcripts from the two defensins were not found in the I. scapularis tick cell lines ISE6 and ISE18. [Conclusion]: Our results have two main implications. Firstly, the anti-Listeria and antifungal activities of Scapularisin-3 and Scapularisin-6 suggest that these peptides may be useful for (i) treatment of antibiotic-resistant L. grayi in humans and (ii) plant protection. Secondly, the antimicrobial properties of the two defensins described in this study may pave the way for further studies regarding pathogen invasion and innate immunity in I. scapularis.Miray Tonk is a Marie Curie Early Stage Researcher supported by the POSTICK ITN (Post-graduate training network for capacity building to control ticks and tick-borne diseases) within the FP7- PEOPLE – ITN programme (EU Grant No. 238511). This project was partially supported by the Grant Agency of the Czech Republic (GACR P302/11/1901) and with institutional support RVO: 60077344 from Biology Centre, Institute of Parasitology as well as grant ANTIGONE (EU-7FP; 278976). James J. Valdés was sponsored by project CZ.1.07/2.3.00/30.0032, co-financed by the European Social Fund and the state budget of the Czech Republic. Radek Šíma was supported by the Grant 13-12816P (GA CR). Mohammad Rahnamaeian and Andreas Vilcinskas acknowledge the Ministry for Science and Art of the State of Hesse (Germany) for funding the LOEWE Center of Insect Biotechnology and Bioresources. Zdeněk Franta was supported by Alexander von Humboldt Research Fellowship for Postdoctoral Researchers.Peer Reviewe

New species of Ehrlichia isolated from Rhipicephalus (Boophilus) microplus shows an ortholog of the E. canis major immunogenic glycoprotein gp36 with a new sequence of tandem repeats

This is an Open Access article distributed under the terms of the Creative Commons Attribution License.-- et al.[Background]: Ehrlichia species are the etiological agents of emerging and life-threatening tick-borne human zoonoses that inflict serious and fatal infections in companion animals and livestock. The aim of this paper was to phylogeneticaly characterise a new species of Ehrlichia isolated from Rhipicephalus (Boophilus) microplus from Minas Gerais, Brazil. [Methods]: The agent was isolated from the hemolymph of Rhipicephalus (B.) microplus engorged females that had been collected from naturally infested cattle in a farm in the state of Minas Gerais, Brazil. This agent was then established and cultured in IDE8 tick cells. The molecular and phylogenetic analysis was based on 16S rRNA, groEL, dsb, gltA and gp36 genes. We used the maximum likelihood method to construct the phylogenetic trees. [Results]: The phylogenetic trees based on 16S rRNA, groEL, dsb and gltA showed that the Ehrlichia spp isolated in this study falls in a clade separated from any previously reported Ehrlichia spp. The molecular analysis of the ortholog of gp36, the major immunoreactive glycoproteins in E. canis and ortholog of the E. chaffeensis gp47, showed a unique tandem repeat of 9 amino acids (VPAASGDAQ) when compared with those reported for E. canis, E. chaffeensis and the related mucin-like protein in E. ruminantium. [Conclusions]: Based on the molecular and phylogenetic analysis of the 16S rRNA, groEL, dsb and gltA genes we concluded that this tick-derived microorganism isolated in Brazil is a new species, named E. mineirensis (UFMG-EV), with predicted novel antigenic properties in the gp36 ortholog glycoprotein. Further studies on this new Ehrlichia spp should address questions about its transmissibility by ticks and its pathogenicity for mammalian hosts.A. Cabezas Cruz is a Marie Curie Early Stage Researcher (ESR) supported by the POSTICK ITN (Post-graduate training network for capacity building to control ticks and tick-borne diseases) within the FP7- PEOPLE – ITN programme (EU Grant No. 238511).Peer Reviewe

Tick-borne encephalitis virus inhibits rRNA synthesis and host protein production in human cells of neural origin

Tick-borne encephalitis virus (TBEV), a member of the genus Flavivirus (Flaviviridae), is a causative agent of a severe neuroinfection. Recently, several flaviviruses have been shown to interact with host protein synthesis. In order to determine whether TBEV interacts with this host process in its natural target cells, we analysed de novo protein synthesis in a human cell line derived from cerebellar medulloblastoma (DAOY HTB-186). We observed a significant decrease in the rate of host protein synthesis, including the housekeeping genes HPRT1 and GAPDH and the known interferon-stimulated gene viperin. In addition, TBEV infection resulted in a specific decrease of RNA polymerase I (POLR1) transcripts, 18S and 28S rRNAs and their precursor, 45-47S pre-rRNA, but had no effect on the POLR3 transcribed 5S rRNA levels. To our knowledge, this is the first report of flavivirus-induced decrease of specifically POLR1 rRNA transcripts accompanied by host translational shut-off